Edited by FiiO - 9/29/12 at 2:27am
This code is Series Number , not the secret code. the secret code is a 20 numbers. Note that now there are quite some stocked FiiO products which without secret code.
As we known, fake E6 does not come with SN label, so don't worry about your E6.
The secret code has 20 numbers so don't missing any number.